Currently, in a Long Term Evolution (LTE) system, a structure of a radio frame is as follows: One radio frame includes 10 subframes, and each subframe includes two timeslots. Generally, timeslots in the 10 subframes are represented according to numbers such as number 0, number 1, number 2, . . . , number 18, and number 19, that is, in a radio frame, a subframe number 1 consists of a timeslot number 0 and a timeslot number 1, a subframe number 1 consists of a timeslot number 2 and a timeslot number 3, . . . , and a subframe number 9 consists of a timeslot number 18 and a timeslot number 19.
An orthogonal frequency division multiplexing (OFDM) technology is used in downlink transmission in the LTE system. In the OFDM technology, a guard interval or a cyclic prefix (CP) may be added preceding each OFDM symbol to eliminate intersymbol interference brought by multipath transmission of a signal. Currently, two CP types are defined in LTE: One is a normal CP, and the other is an extended CP. When the CP type is a normal CP, each timeslot includes seven OFDM symbols, where numbers of the OFDM symbols may be respectively denoted as 0 to 6. When the CP type is an extended CP, a timeslot of a subframe of a radio frame includes six OFDM symbols, where numbers of the OFDM symbols may be respectively denoted as 0 to 5.
One physical resource block (PRB) pair occupies one subframe, that is, two timeslots, in a time domain, and consists of 12 subcarriers in a frequency domain. Exemplarily, as shown in FIG. 1(a), FIG. 1(a) is a schematic structural diagram of one PRB pair exists when a CP type is an extended CP. Each small grid is one resource element (RE), and the PRB pair consists of 12 subcarriers in a frequency domain, and occupies one subframe, that is, two timeslots, corresponding to 12 OFDM symbols, in a time domain. In this case, one PRB pair includes 144 resource elements. Each RE is corresponding to one OFDM symbol in the time domain and one subcarrier in the frequency domain, that is, one small grid in FIG. 1(a). Exemplarily, as shown in FIG. 1(b), FIG. 1(b) is a schematic diagram of one PRB pair exists when a CP type is a normal CP. Each small grid is one RE, and the PRB pair consists of 12 subcarriers in a frequency domain, and occupies one subframe, that is, two timeslots, corresponding to 14 OFDM symbols, in a time domain. In this case, the one PRB pair includes 168 REs. Each RE is corresponding to one OFDM symbol in the time domain and one subcarrier in the frequency domain, that is, one small grid in FIG. 1(b).
A Multimedia Broadcast multicast service Single Frequency Network (MBSFN) transmission manner may be used when a multimedia broadcast multicast service is being transmitted in the LTE system. In the transmission manner, MBSFN data is transmitted from multipath strict time synchronization cells over an air interface at the same time, and user equipment (UE) may receive a signal transmitted through multiple paths. For the UE, multipath transmission received from the multiple cells is equivalent to one-path transmission from a single cell, so that transmission that could have caused inter-cell interference is converted into desired signal energy, which may improve spectral efficiency and a signal to interference plus noise ratio (SINR), and improve coverage performance.
In the prior art, MBSFN data is mapped to a physical multicast channel (PMCH) for transmission. Because a channel for the MBSFN data is actually an aggregate channel from multiple cells, UE needs to perform independent channel estimation when receiving the MBSFN data. In a subframe, to prevent an MBSFN reference signal and another reference signal from mixing, in a current standard protocol, frequency division multiplexing of the PMCH and a physical downlink shared channel (PDSCH) is not permitted, but time division multiplexing of the PMCH and the PDSCH is permitted, that is, some specific subframes may be designed as MBSFN subframes, and the MBSFN subframes may be used to bear the PMCH.
Because a difference between transmission delays of multiple cells is generally greater than a delay spread of a single cell, in the standard protocol, it is specified that the MBSFN subframe uses an extended CP, because a relatively long CP helps reduce intersymbol interference. In addition, an MBSFN reference signal pattern is also modified to improve channel estimation accuracy. As shown in FIG. 3, compared with non-MBSFN data transmission, a quantity of REs in an MBSFN reference signal pattern increases, and a spacing in a frequency domain is tighter. Therefore, a base station and user equipment that comply with the standard protocol can successfully complete MBSFN transmission by using the extended CP and the foregoing MBSFN reference signal pattern. In addition, to adhere to a deployment scenario in which a difference between transmission delays of a signal transmitted in different cells is larger, in LTE, it is considered to use a CP that is longer than the extended CP to eliminate the intersymbol interference as possible. In addition, a smaller subcarrier spacing is designed accordingly to reduce CP overheads. Therefore, with further development of MBSFN transmission, how to avoid a reduction in radio resource utilization of a system is still a problem worthy of further study.